The present invention relates to a water softening device for making soft water by a softening treatment (hardness removal treatment) of raw water that contains hardness components. In particular, the present invention relates to a water softening device that continuously produces soft water by having at least two water softeners installed in parallel with raw water flowing alternately through these water softeners.
As is well known, it is necessary to prevent the adhesion of scales inside cooling and heating machinery such as boilers, water heaters, cooling devices and the like. As a result, devices that remove the hardness components contained in the supplied water are connected to the water supply lines of the cooling and heating machinery. Of these, an automatic regenerating water softener with a system of removing hardness components by using an ion exchange resin has been widely used. This type of water softener uses a Na+ type of ion exchange resin. Metal cations such as Ca2+ or Mg2+ and the like are displaced with Na+ to remove the hardness components. When the above resin becomes saturated by displacement with cations and the resin loses its ability to remove hardness components, the resin is contacted with salt water to regenerate its functioning. In this situation, because soft water cannot be supplied during the regeneration operation, two water softeners are used. Water alternately passes through these water softeners, and soft water is supplied continuously.
With this type of conventional water softening device, the switching of the flow of water to a water softener is conducted by a timer. Due to errors or failures in the timer, there are situations where the plurality of softeners are simultaneously regenerated, and the flow of water is not possible. Alternatively, there are situations where the raw water simultaneously flows through a plurality of water softeners.
In order to overcome these shortcomings, in Japanese Laid Open Patent Publication Number 6-15265, a plurality of water softeners equipped with electromagnetic valves are connected in parallel on a soft water supply channel. Soft water supply operation is conducted alternately in these water softeners. After operating the water softener for a specified time or after passing a specified amount of water, in order to regenerate the ion exchange resin, one of the electromagnetic valves is closed, and a signal is sent via a communication line to the other electromagnetic valve and water softener. The electromagnetic valve is opened to operate the water softener. After a specified amount of time has passed or after a specified amount of water has been passed, this water softener begins its regeneration operation, and this electromagnetic valve is closed, and the other electromagnetic valve is opened. Through the communication line, the water softeners after being regenerated are alternately automatically operated.
With the operation method of this water softener, because the operation signal of one water softener is provided to a controller of the other water softener via a communication line, the regeneration operation and the soft water supply operation in each of the water softeners are never conducted simultaneously.
With the operation control method of the water softening device of the above Japanese Laid Open Patent Publication Number 6-15265, the ion exchange resin is regenerated after operating the water softener for a specified amount of time or after passing a specified amount of water. As a result, when the water quality of the raw water fluctuates and the concentration of hardness components becomes higher, or when the properties of the ion exchange resin within the water softener changes (deteriorates for example), there is the risk of leakage of hardness components.